"The recent Fox TV show, which I saw, is an ingenious and
entertaining assemblage of nonsense. The claim that radiation
exposure during the Apollo missions would have been fatal to the
astronauts is only one example of such nonsense." -- Dr. James Van
Allen

There is too much
radiation in outer space for manned space travel.

This general charge is usually made by people who don't understand
very much at all about radiation. After witnessing the horrors of
Hiroshima and Nagasaki and the tragedy of Chernobyl it is not
surprising that the idea of radiation should elicit an intuitively
fearful reaction. But when you understand the different types of
radiation and what can be done about them, it becomes a manageable
problem to avoid radiation exposure.

It doesn't matter how
difficult or expensive it might have been to falsify the lunar
landings. Since it was absolutely impossible to solve the radiation
problem, the landings had to have been faked.

This is a common method of argument that attempts to prove
something that can't be proven, by disproving something else.
In this case the reader is compelled to accept the conspiracy theory
and all its attendant problems and improbabilities, simply on the
basis that no matter how difficult, absurd, or far-fetched a
particular proposition may be, if it's the only alternative to
something clearly impossible then it must -- somehow -- have come to
pass. This false dilemma is aimed at pushing the reader past healthy
skepticism and into a frame of mind where the absurd seems plausible.

The false dilemma is only convincing if the supposedly impossible
alternative is made to seem truly impossible. And so conspiracists
argue very strenuously that the radiation from various sources spelled
absolute doom for the Apollo missions. They quote frightening
statistics and cite various highly technical sources to try to
establish to the reader that the radiation poses a deadly threat.

But in fact most conspiracists know only slightly more about
radiation than the average reader. This means only a very few people
in the world can dispute their allegations, and the conspiracists can
simply dismiss them as part of the conspiracy.

The Van Allen belts are
full of deadly radiation, and anyone passing through them would be
fried.

Needless to say this is a very simplistic statement. Yes, there
is deadly radiation in the Van Allen belts, but the nature of that
radiation was known to the Apollo engineers and they were able to make
suitable preparations. The principle danger of the Van Allen belts is
high-energy protons, which are not that difficult to shield against.
And the Apollo navigators plotted a course through the thinnest parts
of the belts and arranged for the spacecraft to pass through them
quickly, limiting the exposure.

The Van Allen belts span only about forty degrees of earth's
latitude -- twenty degrees above and below the magnetic equator. The
diagrams of Apollo's translunar trajectory printed in various press
releases are not entirely accurate. They tend to show only a
two-dimensional version of the actual trajectory. The actual
trajectory was three-dimensional. The highly technical reports of
Apollo, accessible to but not generally understood by the public, give
the three-dimensional details of the translunar trajectory.

Each mission flew a slightly different trajectory in order to
access its landing site, but the orbital inclination of the translunar
coast trajectory was always in the neighborhood of 30°. Stated
another way, the geometric plane containing the translunar trajectory
was inclined to the earth's equator by about 30°. A spacecraft
following that trajectory would bypass all but the edges of the Van
Allen belts.

This is not to dispute that passage through the Van Allen belts
would be dangerous. But NASA conducted a series of experiments
designed to investigate the nature of the Van Allen belts, culminating
in the repeated traversal of the Southern Atlantic Magnetic Anomaly
(an intense, low-hanging patch of Van Allen belt) by the Gemini 10
astronauts.

NASA defenders make a
big deal about the Southern Atlantic Magnetic Anomaly, but the Apollo
spacecraft ventured into the more intense parts of the
belts.

True, but the point was to validate the scientific models using
hard data, and to ascertain that a spacecraft hull would indeed
attenuate the radiation as predicted.

We know the space
shuttle passes through the Southern Atlantic Magnetic Anomaly (SAMA),
but since the shuttle astronauts have time in each orbit to recover,
the effects are not felt as strongly. The Apollo astronauts spent
around four hours at a single stretch in the Van Allen belts. [Mary
Bennett]

This is exactly the opposite of the recovery principle. If the
shuttle astronauts spend 30 minutes of each 90-minute orbit passing
through the SAMA, that sums to an exposure of 8 hours per day. The
human body does not recover from radiation in a matter of minutes but
rather hours and days. The damaged tissue must be regenerated. If
radiation exposure is more or less continuous over several days, such
as in the shuttle scenario, the tissue never has time to regenerate
before being damaged by continuing radiation.

A short, intense exposure is safer than continuous or
periodic exposure at lower intensity.

Even though the outlying parts of the Van Allen belts contain more
intense radiation than the SAMA, a four-hour passage followed by days
of relatively little exposure offers a better recovery scenario than
days of accumulated low-level exposure.

The four-hour figure is reasonable, but somewhat arbitrary. Since
the Van Allen belts vary in flux and energy, it's not as if there's a
clearly demarcated boundary. It's a bit like walking over a hill. If
the slope gently increases from flat and level to 30° or so, where
do you say the hill starts?

It would require six
feet (two meters) of lead in order to shield from the Van Allen belts.
The Apollo spacecraft had nowhere near this amount of shielding and so
could not have provided the astronauts adequate
protection.

The "six feet of lead" statistic appears in many conspiracist
charges, but no one has yet owned up to being the definitive source of
that figure. In fact, six feet (2 m) of lead would probably shield
against a very large atomic explosion, far in excess of the normal
radiation encountered in space or in the Van Allen belts.

While such drastic measures are needed to shield against intense,
high-frequency electromagnetic radiation, that is not the nature of
the radiation in the Van Allen belts. In fact, because the Van Allen
belts are composed of high-energy protons and high-energy electrons,
metal shielding is actually counterproductive because of the
Bremsstrahlung that would be induced.

Metals can be used to shield against particle radiation,
but they are not the ideal substance. Polyethylene is the choice of
particle shielding today, and various substances were available to the
Apollo engineers to absorb Van Allen radiation. The fibrous
insulation between the inner and outer hulls of the command module was
likely the most effective form of radiation shielding. When metals
must be used in spacecraft (e.g., for structural strength) then a
lighter metal such as aluminum is better than heavier metals such as
steel or lead. The lower the atomic number, the less Bremsstrahlung.

The notion that only vast amounts of a very heavy metal could
shield against Van Allen belt radiation is a good indicator of how
poorly though out the conspiracist radiation case is. What the
conspiracists say is the only way of shielding against the Van
Allen belt radiation turns out to be the worst way to attempt
to do it!

Official NASA documents
describing the pre-Apollo studies of the Van Allen belts clearly state
that shielding was recommended for the Apollo spacecraft, yet no
shielding was provided. [Mary Bennett and David Percy]

"Shielding" does not always mean thick slabs of dense material.

Commensurate with the common perception of radiation as an
inescapably deadly force is the notion of radiation shielding as
universally heavy and dense. Percy and others seem to rely on the
notion that radiation shielding, if present, would have been very
conspicuous -- or prohibitively bulky.

As discussed in the previous question, shielding against particles
is not the same as shielding against rays. To say that the Apollo
spacecraft did not provide adequate shielding is to ignore both the
construction of the Apollo command module and the principles of
radiation shielding.

And it must be kept in mind that shielding was only one element of
a multi-pronged solution for safely traversing the Van Allen belts.
It was never intended that the shielding in the command module would
provide the only protection for the astronauts. The shielding was
adequate to protect the astronauts against the circumstances of the
trajectory and exposure duration worked out by the mission planners.

Fig. 1 - The aurora produced by the Starfish Prime
high-altitude nuclear detonation.

The authors give no reference for the claim that this artificial
radiation belt was "a hundred times" more "intense" than the
naturally-occurring belts. Nor do they define what is meant by
"intense". The Starfish Prime test did in fact produce a temporary
artificial radiation belt, and it's true that this belt persisted
longer than anticipated. But it was not an impediment to the Apollo
missions because it had dissipated to a safe level by then, and was
very small (and easily avoided) to start with.

Radioactive half-life applies to radioisotopes only. It does not
apply to clouds of magnetically-retained charged particles. The
authors imply that their theory is confirmed by expert authors, but in
fact the author they cite discusses only the general concept of
radioactive half-life. Bennett and Percy are responsible for having
misapplied it to this problem. Radioactive half-life and particle
belts have nothing at all to do with each other. The dispersal of
this belt doesn't have anything to do with radioactive decay, and a
great deal to do with solar weather and shifting magnetic fields.

The authors argue that such a radiation belt would still be highly
intense to this day. However they have shown no evidence that any of
the radiation from Starfish Prime is still there. Instead they refer
to irrelevant scientific principles and claim it "must" still be there.

A secret study done by
the Soviet Union and obtained by the CIA determined that a meter of
lead would be required to shield against deep space
radiation.

Many conspiracists allude to this alleged report, but none of them
can attest to actually having seen it. Since they can argue the
alleged report is closely held by the CIA and therefore still top
secret, the conspiracists are protected from refutation. No one can
prove the non-existence of any document, much less one that is
allegedly classified by an intelligence agency. Unfortunately it's
more straightforward to note that the conspiracists cannot expect the
world to accept an argument based on evidence which they cannot
produce. If it's so top secret, how do they know about it?

It's fairly easy to show that such a document likely does not
exist. We know that great thicknesses of lead are not required to
shield against particle radiation. We know that Soviet science and
engineering were excellent. We note with no small amusement and no
small suspicion that the conclusion of the alleged report contradicts
the commonly accepted principles of physics, and that it instead bears
a striking resemblance to the naive assertions of inexpert conspiracy
theorists who claim that only thick sheets of lead are suitable for
radiation shielding. The alleged report is plausible to the lay
reader but utterly unconvincing to the scientist.

The Soviet lunar spacecraft design demonstrates they did not
believe a meter or two of lead was required to shield against
radiation.

History provides the final proof. Had the Soviets actually
believed that great thicknesses of material were required to shield
against radiation, they would have questioned the design of the Apollo
spacecraft. The spacecraft clearly did not provide a meter of lead
shielding, yet NASA claims it successfully traversed the Van Allen
belts. Yet the Soviets acknowledged then and continue to acknowledge
today that the Apollo program was a clear success.

In recent years the Western world has been able to examine the
Soviet spacecraft design which was to have carried cosmonauts to the
moon. They did not provide a meter of lead for their spacecraft
either.

Soviet cosmonauts have
been quoted as saying radiation was a very grave concern.

And NASA officials have been quoted as saying essentially the same
thing. Radiation is a very great concern, but there's a vast
difference between a "concern" and an insurmountable obstacle. The
conspiracist argument relies on the radiation problem being
insurmountable, and nothing said by either NASA or cosmonauts conveys
the notion that these problems couldn't have been solved.